1. Field of the Invention
This invention relates to safety couplings for preventing dangerous spillage of fluids upon disconnection of a pipe coupling, and more particularly, to quick disconnect couplings which automatically seal a pipeline or hose at the point of breakage when sections of the hose are pulled apart or disconnected, whether by intention or accidentally.
2. Brief Description of the Prior Art
A number of types of quick disconnect couplings are manufactured and are used to convey fluids in a number of types of industrial usage. One type of such couplings includes male and female sections which are telescoped or joined together with a sealing fit by means of leverage or a camming action which facilitates rapid connection without the need for a screw connection or a bolted connection involving placement of a number of nuts, or similar time-consuming operations. Quick disconnect couplings of this type are of the sort illustrated and described in Krapp U.S. Pat. No. 2,641,490, Parrish U.S. Pat. No. 3,195,934, and U.S. Pat. No. 2,478,586 to Krapp.
Whether a quick disconnect coupling or a bolted coupling is employed to join flexible pipe or hose sections, a danger of spillage of inflammable or explosive liquids exists where such couplings are used in conduits, pipes or hoses for transferring volatile, inflammable or explosive liquids from a transport truck to a storage facility. Typical of this type of operation is that where gasoline is transferred from a tank truck to the underground storage tanks at a service station, or to other storage facilities. Here accidents are not infrequently caused by a truck driver inadvertently driving the tanker vehicle away from the stationary storage tank prior to the time that service is shut off. As a result, the hose is inadvertently pulled free at the locus of the coupling by the shearing of connecting bolts, or breaking of camming levers and pins. Where this occurs, a very hazardous, situation is developed which may cause serious injury or loss of life due to igniting or explosion of the liquid. Even where the liquid is not ignited, and no hazard to safety is thereby developed, loss of the liquid product through spillage is often very costly where such a premature parting of the coupling results from the accidental drive-away incident described.
Recently, several attempts have been made to provide break-away couplings which will respond to tension imparted to the product line in which they are located by breaking power, but which will, simultaneously with such breaking or parting of the coupling, automatically close the opposed ends of the pipe or hose which carry the coupling parts. The liquid product is thus prevented from flowing out of the thus opened ends of the pipe at the location of the severed coupling. In one such coupling manufactured by Alpha Process Controls, Ltd. and called the A.P.C. breakaway coupling, the coupling is opened by the breaking of shear bolts used to hold the coupling parts together, and upon the opening of the coupling, valve elements carried in the two coupling parts are forced by suitable springs into closing engagement with the openings at the open end of each coupling part. Liquid contained within the two parts of the hose or pipe is thus confined and not allowed to spill upon the ground and constitute a safety hazard.
As indicated, the A.P.C. breakaway coupling relies, in its coupled status, upon the utilization of a plurality of shear bolts which require the threading of nuts on the ends of these bolts to effect coupling when product is to be discharged from a tank truck to a storage facility. Further, at the time that the shear bolts are tensioned due to inadvertent driving of the truck away from the storage facility receiving product from the truck, a flexible hose is also placed in tension and is stressed, thereby either decreasing its effective service life, or if it is already weak, possibly parting this hose at a location spaced along the hose from the breakaway coupling, thus destroying the effectiveness of the shut-off, and allowing liquid to spill through the break in the hose to develop a safety hazard, and result in a substantial loss of product.